The present invention relates to a magneto-optical recording apparatus for recording an information signal on a magneto-optical recording medium on which an information signal is recorded by a magnetic field modulation recording method, a magnetic head used for the magneto-optical recording apparatus, and a magnetic head coil used for the magnetic head.
A conventionally known example of magneto-optical recording apparatuses for recording information signals at high density on a magneto-optical recording medium such as a magneto-optical disk adopts a magnetic field modulation method. The apparatus of this type comprises optical and magnetic heads. The optical head converges a laser beam into a small light spot to irradiate the magnetic recording layer of a magneto-optical recording medium. The magnetic head vertically applies a magnetic field modulated by an information signal to the laser beam irradiated portion of the magneto-optical recording medium, thereby recording the information signal on the magneto-optical recording medium.
This conventional magneto-optical recording apparatus uses a magnetic head having an arrangement as disclosed in, e.g., Japanese Patent Application Laid-open No. 6-309607. FIG. 9 is a sectional view showing the structure of this conventional magnetic head.
Reference numeral 50 denotes a core made of a magnetic material such as ferrite; and 51, a coil formed by winding a magnetic wire (thin electric wire prepared by forming an insulating film of polyurethane or the like on a conductive wire made of a conductive material such as copper) on a magnetic pole p3 of the core. By supplying a current to the coil 51, a magnetic field is generated from the end face of the magnetic pole p3 of the core 50, and vertically applied to a magneto-optical recording medium.
In recent years, demands have arisen for high-speed recording of an information signal. Along with this, the modulation frequency of the magnetic field must be increased. However, when the coil is formed from a magnetic wire, like the conventional magnetic head, the sectional shape and size of a manufacturable conductive wire are limited and cannot be arbitrarily set. If the diameter of the conductive wire forming the magnetic wire is set to 50 xcexcm or less to downsize the coil, the magnetic wire is difficult to align vertically and horizontally, as shown in FIG. 9, so as to constitute the coil. This results in irregular turns of the disordered winding. For this reason, the coil diameter is inevitably large. For a vertically elongated coil shape, as shown in FIG. 9, the coil inductance increases so as to decrease the magnetic field generation efficiency of the magnetic head. However, a thin magnetic wire made of a conductive wire 50 xcexcm or less in diameter is very difficult to manufacture not as a vertically elongated coil but as a flat coil with a low inductance. To increase the modulation frequency of the magnetic field, a high drive voltage proportional to the modulation frequency or coil inductance must be applied to the magnetic head coil, which increases the power consumption of the magneto-optical recording apparatus. In addition, the RF resistance of the coil caused by the skin and proximity effects of the magnetic wire cannot be satisfactorily reduced. The RF loss of the magnetic head increases, heat generated by the magnetic head degrades the magnetic characteristics of the magnetic head, and a magnetic field of a desired strength is difficult to generate. This problem becomes serious at a maximum magnetic field modulation frequency of 8 MHz or more.
According to the present invention, a flat magnetic head coil constituted by spiral coil patterns made of a conductive material film and two terminals connected to the coil patterns is characterized in that the coil patterns have a substantially rectangular sectional shape, a minimum pitch P [xcexcm] of the coil pattern, a width W [xcexcm] of the sectional shape at the minimum pitch P, and a height H [xcexcm] satisfy inequalities (10) and (11):
15 [xcexcm]xe2x89xa6Pxe2x89xa670 [xcexcm]xe2x80x83xe2x80x83(10)
1.85xe2x88x920.012Pxe2x89xa6H/Wxe2x89xa67.5xe2x88x920.06Pxe2x80x83xe2x80x83(11)
when an impedance Z0 between the two terminals of the coil while at least a core made of a magnetic material is not attached is regarded to be equivalently constituted by an inductance L0, an RF resistance Rp0 parallel to the inductance L0, and a DC resistance Rs which is series-connected to the inductance L0 and is independent of a frequency, the inductance L0 [xcexcH] at 10 MHz satisfies inequality (5):
L0xe2x89xa60.85 [xcexcH]xe2x80x83xe2x80x83(5)
The magnetic head coil is characterized in that the inductance L0 [xcexcH] at 10 MHz, and the RF resistance Rp0 [xcexa9] at 20 MHz and the DC resistance Rs [xcexa9] satisfy inequalities (6) and (8):
Rp0xe2x89xa7L0xc3x971500xe2x80x83xe2x80x83(6)
Rsxe2x89xa62xe2x80x83xe2x80x83(8)
The magnetic head coil is characterized in that the inductance L0 [xcexcH] at 10 MHz, and the RF resistance Rp0 [xcexa9] at 20 MHz satisfy inequality (7):
xe2x80x83Rp0xe2x89xa7L0xc3x972000xe2x80x83xe2x80x83(7)
The magnetic head coil is characterized in that at least one of the coil patterns is formed on a lower surface side of the magnetic head coil facing a magneto-optical recording medium, and an interval Tb [xcexcm] between the coil patterns, an interval Tc [xcexcm] between an end face of the coil pattern formed on the lower surface side and a lower surface of the magnetic head coil, and a thickness T [xcexcm] of the magnetic head coil satisfy inequalities (13), (14), and (15):
2 [xcexcm]xe2x89xa6Tbxe2x89xa670 [xcexcm]xe2x80x83xe2x80x83(13)
Tcxe2x89xa61.5Hxe2x80x83xe2x80x83(14)
50 [xcexcm]xe2x89xa6Txe2x89xa6450 [xcexcm]xe2x80x83xe2x80x83(15)
The magnetic head coil is characterized in that a total number N of turns of the coil patterns, a minimum radius r1 [mm] of an innermost periphery of the coil pattern, and a maximum radius r2 [mm] of an outermost periphery satisfy inequalities (16), (17), and (18):
14xe2x89xa6Nxe2x89xa640xe2x80x83xe2x80x83(16)
r1xe2x89xa60.2 [mm]xe2x80x83xe2x80x83(17)
r2xe2x89xa61.1 [mm]xe2x80x83xe2x80x83(18)
According to the present invention, a flat magnetic head coil constituted by spiral coil patterns made of a conductive material film and two terminals connected to the coil patterns is characterized in that a light-transmitting portion is formed at a center of the coil, the coil patterns have a substantially rectangular sectional shape, a minimum pitch P [xcexcm] of the coil pattern, a width W [xcexcm] of the sectional shape at the minimum pitch P, and a height H [xcexcm] satisfy inequalities (29) and (30):
15 [xcexcm]xe2x89xa6Pxe2x89xa650 [xcexcm]xe2x80x83xe2x80x83(29)
1.85xe2x88x920.012Pxe2x89xa6H/Wxe2x89xa67.5xe2x88x920.06Pxe2x80x83xe2x80x83(30)
when an impedance Z0 between the two terminals of the coil while at least a core made of a magnetic material is not attached is regarded to be equivalently constituted by an inductance L0, an RF resistance Rp0 parallel to the inductance L0, and a DC resistance Rs which is series-connected to the inductance L0 and is independent of a frequency, the inductance L0 [xcexcH] at 10 MHz satisfies inequality (24):
L0xe2x89xa61.4 [xcexcH]xe2x80x83xe2x80x83(24)
The magnetic head coil is characterized in that the inductance L0 [xcexcH] at 10 MHz, and the RF resistance Rp0 [xcexa9] at 20 MHz and the DC resistance Rs [xcexa9] satisfy inequalities (25) and (27):
Rp0xe2x89xa7L0xc3x971200xe2x80x83xe2x80x83(25)
Rsxe2x89xa66[xcexa9]xe2x80x83xe2x80x83(27)
The magnetic head coil is characterized in that the inductance L0 [xcexcH] at 10 MHz, and the RF resistance Rp0 [xcexa9] at 20,MHz satisfy inequality (26):
Rp0xe2x89xa7L0xc3x971500xe2x80x83xe2x80x83(26)
The magnetic head coil is characterized in that at least one of the coil patterns is formed on a lower surface side of the magnetic head coil facing a magneto-optical recording medium, and an interval Tb [xcexcm] between the coil patterns, an interval Tc [xcexcm] between an end face of the coil pattern formed on the lower surface side and a lower surface of the magnetic head coil, and a thickness T [xcexcm] of the magnetic head coil satisfy inequalities (32), (33), and (34):
2 [xcexcm]xe2x89xa6Tbxe2x89xa670 [xcexcm]xe2x80x83xe2x80x83(32)
Tcxe2x89xa61.5Hxe2x80x83xe2x80x83(33)
30 [xcexcm]xe2x89xa6Txe2x89xa6300 [xcexcm]xe2x80x83xe2x80x83(34)
The magnetic head coil is characterized in that a total number N of turns of the coil patterns, a minimum radius r1 [mm] of an innermost periphery of the coil pattern, and a maximum radius r2 [mm] of an outermost periphery satisfy inequalities (35), (36), and (37):
20xe2x89xa6Nxe2x89xa670xe2x80x83xe2x80x83(35)
r1xe2x89xa60.13 [mm]xe2x80x83xe2x80x83(36)
r2xe2x89xa61.0 [mm]xe2x80x83xe2x80x83(37)
The magnetic head coil is characterized in that when at least a core made of a magnetic material is not attached, a self-resonance frequency fr0 [MHz] which maximizes an impedance magnitude |Z0| of the coil, and the inductance L0 [xcexcH] at 10 MHz satisfy inequality (9):
fr0xe2x89xa71/(2xcfx80{square root over (L0xc3x971.4xc3x9710xe2x88x926)})xe2x80x83xe2x80x83(9)
The magnetic head coil is characterized in that two to four coil patterns are formed.
The magnetic head coil is characterized in that the pitch P [xcexcm] and the width W [xcexcm] on the coil pattern satisfy inequality (12):
0.55xe2x89xa6W/Pxe2x89xa60.8xe2x80x83xe2x80x83(12)
According to the present invention, a magnetic head having a core made of a magnetic material and a flat coil is characterized in that the coil is constituted by spiral coil patterns made of a conductive material film and two terminals connected to the coil patterns, the coil patterns have a substantially rectangular sectional shape, a minimum pitch P [xcexcm] of the coil pattern, a width W [xcexcm] of the sectional shape at the minimum pitch P, and a height H [xcexcm] satisfy inequalities (10) and (11):
15 [xcexcm]xe2x89xa6Pxe2x89xa670 [xcexcm]xe2x80x83xe2x80x83(10)
1.85xe2x88x920.012Pxe2x89xa6H/Wxe2x89xa67.5xe2x88x920.06Pxe2x80x83xe2x80x83(11)
when an impedance Z1 between the two terminals of the coil is regarded to be equivalently constituted by an inductance L1, an RF resistance Rp1 parallel to the inductance L1, and a DC resistance Rs which is series-connected to the inductance L1 and is independent of a frequency, the inductance Li [xcexcH] at 10 MHz satisfies inequality (1):
L1xe2x89xa61.4 [xcexcH]xe2x80x83xe2x80x83(1)
The magnetic head is characterized in that the inductance L1 [xcexcH] at 10 MHz, and the RF resistance Rp1 [xcexa9] at 20 MHz and the DC resistance Rs [xcexa9] satisfy inequalities (2) and (8):
Rp1xe2x89xa7L1xc3x971500xe2x80x83xe2x80x83(2)
Rsxe2x89xa62[xcexa9]xe2x80x83xe2x80x83(8)
The magnetic head is characterized in that the inductance L1 [xcexcH] at 10 MHz, and the RF resistance Rp1 [xcexa9] at 20 MHz satisfy inequality (3):
Rp1xe2x89xa7L1xc3x972000xe2x80x83xe2x80x83(3)
The magnetic head is characterized in that at least one of the coil patterns is formed on a lower surface side of the coil facing a magneto-optical recording medium, and an interval Tb [xcexcm] between the coil patterns, an interval Tc [xcexcm] between an end face of the coil pattern formed on the lower surface side and a lower surface of the coil, and a thickness T [xcexcm] of the coil satisfy inequalities (13), (14), and (15):
2 [xcexcm]xe2x89xa6Tbxe2x89xa670 [xcexcm]xe2x80x83xe2x80x83(13)
Tcxe2x89xa61.5Hxe2x80x83xe2x80x83(14)
50 [xcexcm]xe2x89xa6Txe2x89xa6450 [xcexcm]xe2x80x83xe2x80x83(15)
The magnetic head is characterized in that a total number N of turns of the coil patterns, a minimum radius r1 [mm] of an innermost periphery of the coil pattern, and a maximum radius r2 [mm] of an outermost periphery satisfy inequalities (16), (17), and (18):
14xe2x89xa6Nxe2x89xa640xe2x80x83xe2x80x83(16)
xe2x80x83r1xe2x89xa60.2 [mm]xe2x80x83xe2x80x83(17)
r2xe2x89xa61.1 [mm]xe2x80x83xe2x80x83(18)
The magnetic head is characterized in that the magnetic head has a sliding surface for sliding on a magneto-optical recording medium or a floating surface for floating and gliding, and an interval d [xcexcm] between a lower surface of the coil facing the magneto-optical recording medium and a lowest point of the sliding surface or the floating surface satisfies inequality (19):
dxe2x89xa6200 [xcexcm]xe2x80x83xe2x80x83(19)
According to the present invention, a magnetic head having a flat coil is characterized in that the coil is constituted by spiral coil patterns made of a conductive material film and two terminals connected to the coil patterns, a light-transmitting portion is formed at a center of the coil, the coil patterns have a substantially rectangular sectional shape, a minimum pitch P [xcexcm] of the coil pattern, a width W [xcexcm] of the sectional shape at the minimum pitch P, and a height H [xcexcm] satisfy inequalities (29) and (30):
15 [xcexcm]xe2x89xa6Pxe2x89xa650 [xcexcm]xe2x80x83xe2x80x83(29)
1.85xe2x88x920.012Pxe2x89xa6H/Wxe2x89xa67.5xe2x88x920.06Pxe2x80x83xe2x80x83(30)
when an impedance Z1 between the two terminals of the coil is regarded to be equivalently constituted by an inductance L1, an RF resistance Rp1 parallel to the inductance L1, and a DC resistance Rs which is series-connected to the inductance L1 and is independent of a frequency, the inductance L1 [xcexcH] at 10 MHz satisfies inequality (20):
L1xe2x89xa61.4 [xcexcH]xe2x80x83xe2x80x83(20)
The magnetic head is characterized in that the inductance L1 [xcexcH] at 10 MHz, and the RF resistance Rp1 [xcexa9] at 20 MHz and the DC resistance Rs [xcexa9] satisfy inequalities (21) and (27):
Rp1xe2x89xa7L1xc3x971200xe2x80x83xe2x80x83(21)
Rsxe2x89xa66[xcexa9]xe2x80x83xe2x80x83(27)
The magnetic head is characterized in that the inductance L1 [xcexcH] at 10 MHz, and the RF resistance Rp1 [xcexa9] at 20 MHz satisfy inequality (22):
Rp1xe2x89xa7L1xc3x971500xe2x80x83xe2x80x83(22)
The magnetic head is characterized in that at least one of the coil patterns is formed on a lower surface side of the coil facing a magneto-optical recording medium, and an interval Tb [xcexcm] between the coil patterns, an interval Tc [xcexcm] between an end face of the coil pattern formed on the lower surface side and a lower surface of the coil, and a thickness T [xcexcm] of the coil satisfy inequalities (32), (33), and (34):
2 [xcexcm]xe2x89xa6Tbxe2x89xa670 [xcexcm]xe2x80x83xe2x80x83(32)
Tcxe2x89xa61.5Hxe2x80x83xe2x80x83(33)
30 [xcexcm]xe2x89xa6Txe2x89xa6300 [xcexcm]xe2x80x83xe2x80x83(34)
The magnetic head is characterized in that a total number N of turns of the coil patterns, a minimum radius r1 [mm] of an innermost periphery of the coil pattern, and a maximum radius r2 [mm] of an outermost periphery satisfy inequalities (35), (36), and (37):
20xe2x89xa6Nxe2x89xa670xe2x80x83xe2x80x83(35)
r1xe2x89xa60.13 [mm]xe2x80x83xe2x80x83(36)
r2xe2x89xa61.0 [mm]xe2x80x83xe2x80x83(37)
The magnetic head is characterized in that the magnetic head has a sliding surface for sliding on a magneto-optical recording medium or a floating surface for floating and gliding, and an interval d [xcexcm] between a lower surface of the coil facing the magneto-optical recording medium and a lowest point of the sliding surface or the floating surface satisfies inequality (38):
dxe2x89xa6100 [xcexcm]xe2x80x83xe2x80x83(38)
The magnetic head is characterized in that a self-resonance frequency fr1 [MHz] which maximizes an impedance magnitude |Z1| of the coil, and the inductance L1 [xcexcH] at 10 MHz satisfy inequality (4):
fr1xe2x89xa71/(2xcfx80{square root over (L1xc3x971.4xc3x9710xe2x88x926)})xe2x80x83xe2x80x83(4)
The magnetic head is characterized in that two to four coil patterns are formed.
The magnetic head is characterized in that the pitch P [xcexcm] and the width W [xcexcm] on the coil pattern satisfy inequality (12):
0.55xe2x89xa6W/Pxe2x89xa60.8xe2x80x83xe2x80x83(12)
The magnetic head according to the present invention is characterized by further comprising a lens.
According to the present invention, a magneto-optical recording apparatus having an optical head for irradiating a magneto-optical recording medium with light, and a magnetic head for applying a magnetic field modulated by an information signal to the magneto-optical recording medium is characterized in that the magnetic head is a magnetic head having some of the above features.
Using the magnetic head coil, magnetic head, and magneto-optical recording apparatus according to the present invention can solve the above-described problem in the conventional apparatus.